1. Field of the Disclosure
This disclosure is related to antenna systems; specifically to a wide band antenna tracking systems.
2. Related Art
High gain antennas provide highly directional beams. While these antenna can provided high receive sensitivity, pointing of the antenna to the incoming electromagnetic wave is critical in maintaining this sensitivity. This is especially critical in space applications where pointing errors can seriously degrade system performance.
For any mode of transmission of a microwave signal in a circular waveguide, the electric and magnetic transverse fields may each be resolved into a respective set of tangential and radial components. Those skilled in the art of microwave theory are aware that both the tangential and radial components vary periodically in amplitude along a circular path, which is concentric with a wall of the waveguide, and also vary in amplitude along any given radius in a manner related to a Bessel function of an order m.
Modes of a transverse electric (TE) field are identified by the notation TEmn and modes of a transverse magnetic (TM) field are identified by the notation TMmn, where m represents the total number of full period variations of either the tangential or radial component of the respective electric or magnetic field along a circular path concentric with the wall of the waveguide, and n represents one more than the total number of reversals of polarity of either the tangential or the radial component of the respective electric or magnetic field along a radial path.
In a waveguide that can support more than one propagation mode, the mode that propagates with minimum degradation is designated as the dominant mode. The dominant mode in circular waveguides may be denoted as the TE11 mode, which corresponds to the TE10 mode in rectangular waveguides. In this disclosure, the term “dominant mode” and “primary mode” are used interchangeably.
Conventional antenna tracking systems today are undesirable because they are generally used in single frequency applications. For wideband, frequency applications, conventional systems use asymmetric waveguide modes such as TE21 (Transverse Electric 21) or TM01 (Transverse Magnetic 01) modal couplers. These modal couplers are heavy and use a complex waveguide network in signal combination, and hence are undesirable. Therefore, it is advantageous to have a compact wideband antenna tracking modulator for antenna based signal tracking.